Significance of revised criteria for chronic active T cell-mediated rejection in the 2017 Banff classification: Surveillance by 1-year protocol biopsies for kidney transplantation.

Diagnostic criteria for chronic active T-cell mediated rejection (CA-TCMR) were revised in the Banff 2017 consensus, but it is unknown whether the new criteria predict graft prognosis of kidney transplantation. We enrolled 406 kidney allograft recipients who underwent a 1-year protocol biopsy (PB) and investigated the diagnostic significance of Banff 2017. Interobserver reproducibility of the three diagnosticians showed a substantial agreement rate of 0.68 in Fleiss's kappa coefficient. Thirty-three patients (8%) were classified as CA-TCMR according to Banff 2017, and 6 were previously diagnosed as normal, 12 as acute TCMR, 10 with borderline changes, and 5 as CA-TCMR according to Banff 2015 criteria. Determinant factors of CA-TCMR were cyclosporine use (vs. tacrolimus), previous acute rejection, and BK polyomavirus-associated nephropathy. In survival analysis, the new diagnosis of CA-TCMR predicted a composite graft endpoint defined as doubling serum creatinine or death-censored graft loss (log-rank test, P<0.001). In multivariate analysis, CA-TCMR was associated with the second highest risk of the composite endpoint (hazard ratio: 5.42; 95% confidence interval, 2.02-14.61; P<0.001, vs. normal) behind antibody-mediated rejection. In conclusion, diagnosis of CA-TCMR in Banff 2017 may facilitate detecting an unfavorable prognosis of kidney allograft recipients who undergo a 1-year PB.